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| United States Patent |
6,207,196
|
|
Rigal
, et al.
|
March 27, 2001
|
Vegetable base material from cereal plants and process for obtaining the
same
Abstract
A material formed from plant matter granules has the following size
distribution, the percentages being expressed by weight of dry matter:
between about 5 and 50% of the granules having a size of less than about
0.25 mm, between about 5 and 40% of the granules having a size of between
about 0.25 and 0.5 mm, between about 15 and 60% of the granules having a
size of between about 0.5 and 1 mm, between about 1 and 10% of the
granules having a size of between about 1 and 1.25 mm, between about 0.5
and 7% of the granules having a size of between about 1.25 and 1.4 mm,
between about 1 and 10% of the granules having a size of between about 1.4
and 1.7 mm, between about 0.1 and 10% of the granules having a size of
between about 1.7 and 2.36 mm, and between about 0 and 10% of the granules
having a size greater than about 2.36 mm.
| Inventors:
|
Rigal; Luc (Saint-Jean, FR);
Peyrat; Eric (Toulouse, FR);
Pluquet; Vincent (Madiran, FR);
Gaset; Antoine (Toulouse, FR)
|
| Assignee:
|
Societe Cooperative Agricole Vivadour (Riscle, FR)
|
| Appl. No.:
|
405166 |
| Filed:
|
September 24, 1999 |
Foreign Application Priority Data
| Current U.S. Class: |
424/489; 424/499 |
| Intern'l Class: |
A61K 9/1/6; 9./36 |
| Field of Search: |
424/195.1,499,494,490,461,480,489
241/24,48,51,74,86.1,5,49
514/781
|
References Cited
U.S. Patent Documents
| 3771294 | Nov., 1973 | Ronning | 55/345.
|
Primary Examiner: Weber; Jon P.
Assistant Examiner: Patten; Patricia A
Attorney, Agent or Firm: Young & Thompson
Claims
What is claimed is:
1. A material formed from plant matter granules wherein said plant matter
granules possess the following size distribution, the percentages being
expressed by weight of dry matter:
between about 5 and 50% of the granules having a size of less than about
0.25 mm,
between about 5 and 40% of the granules having a size of between about 0.25
and 0.5 mm,
between about 15 and 60% of the granules having a size of between about 0.5
and 1 mm,
between about 1 and 10% of the granules having a size of between about 1
and 1.25 mm,
between about 0.5 and 7% of the granules having a size of between about
1.25 and 1.4 mm,
between about 1 and 10% of the granules having a size of between about 1.4
and 1.7 mm,
between about 0.1 and 10% of the granules having a size of between about
1.7 and 2.36 mm, and
between about 0 and 10% of the granules having a size greater than about
2.36 mm.
2. The material of claim 1 which possesses a tensile strength of at least
10 N/mm.sup.2 and a tension modulus of at least 1500 N/mm.sup.2.
3. The material of claim 1 which possesses a bending strength of at least
20 N/mm.sup.2 and a bending modulus of at least 1500 N/mm.sup.2.
4. The material according to claim 1, wherein said material has the
following composition, the percentages being expressed in weight of dry
matter:
between about 20% and 60% of starch,
between about 3 and 20% of proteins,
between about 15 and 60% of the total of cellulose, hemicellulose and
lignin,
between about 1 and 15% of lipids and,
between about 0.01 and 10% of sugars.
5. The material according to claim 1 which is in form of hollow, solid or
profiled shapes.
Description
FIELD OF THE INVENTION
The present invention relates to a plant-based material derived from the
above-ground parts of cereal plants or from major fractions of these.
It also relates to a process for preparing such material.
BACKGROUND OF THE INVENTION
In recent years, there has been considerable development in biomaterials,
mainly for ecological reasons.
In general, these materials are either materials reconstituted from
products isolated from plants, or products isolated from plants mixed with
synthetic materials, such as polymers. A commercially available product
composed of a combination of a synthetic biopolymer and wheat, corn or
potato starch, is an example of a material in this latter category.
Several polymers may be combined with starch, such as polyvinyl chloride,
polyethylene or polyvinyl alcohol.
In the first category are materials obtained by combination of starch with
plant fibers.
However, these products have limited mechanical properties and are often
sensitive to water.
U.S. Pat. No. 5,683,772 discloses compositions, which may be used as
packaging materials, containing a starch-based binder, an inorganic
filler, and fibers dispersed uniformly in the starch matrix. These fibers
may include cellulose fibers, and may be obtained from leaves, stems, or
other parts of the plant.
However, these fibers, and the starch, must necessarily be isolated, which
considerably increases the manufacturing costs.
Application WO 95/04 111 discloses articles composed of a material
containing wood particles impregnated with acid resin and a binder, which
may be starch and/or proteins. In this material, the wood particles must
necessarily be impregnated with resins and plant oils or fats.
U.S. Pat. No. 5,160,368 relates to a process for manufacturing packaging
materials, comprising the production of a paste by heating a flour, from a
graminaceous plant. This paste is mixed with crushed hay.
This process necessarily requires the production of the flour from the
graminaceous plant, then its cooking, before admixture with the hay. There
is thus no direct mixing of the grain and the hay.
It thus emerges from the state of the art that there is no known process
for producing coherent materials from raw plant matter, in other words
from plant matter not having been subjected to separation, or isolation of
its different components.
One of the problems posed to a person skilled in the art lies in the
heterogeneity of the components within a single plant tissue, and even
more between two different tissues. In fact, in a whole cereal plant, the
fibers have very different characters according to the part of the plant,
both in their composition and shape. Thus, fibers of wheat straw or of the
outer part of the stems and leaves of corn are long fibers, rich in
cellulose (40-45% of dry matter), relatively ligneous (15% of dry matter),
the remainder being composed of hemicelluloses, of xylan type structure.
The fibers of corn bran or wheat bran (grain coating) are very different,
being short, elastic, much richer in hemicelluloses (up to 60% of dry
matter of the fibers against 15% of cellulose and 8% of lignin). In
addition, these hemicelluloses are of arabinoxylan type, much more highly
substituted than the stem xylans, and with thickening and gelling
properties in solution in water, in fact filmogenic properties. The fibers
of the outer part of the corn cob (hard part) are very different from
those of the central or inner part (tender or soft part). The former are
very hard, proportionally richer in cellulose (47%) and in lignin (7%) and
less in hemicelluloses (37%), while the latter are soft, proportionally
less rich in cellulose (35%) and in lignin (5%). The water-absorbent power
of the soft fibers is seven times greater than that of the hard fibers.
SUMMARY OF THE INVENTION
The applicant has solved the problem of the heterogeneity of the components
by treatment of the whole plant under specific conditions.
The object of the present invention is thus a process for preparing a
plant-based material derived from at least one whole cereal plant
comprising the following steps:
a) cutting the whole of the above-ground parts of the plant, or a major
fraction of them, into fragments,
b) grinding, or shearing, the fragments into granules with an average size
of between about 0.01 and 10 mm,
c) adjusting the water content of the granules until an overall hydration
level of between 10 and 35% is achieved, and
d) forming the material.
If the residual humidity level of the fragments obtained from step a) is
too high, said fragments may be dried to a residual humidity level of
between bout 5 and 20%. Such treatment may in particular be necessary when
the plant matter is corn.
The above-ground parts of the plant should be particularly understood
include the stems, leaves, cobs, grain, husks, but also any other
above-ground part which may be present, as a function of the plant variety
and species.
The plant matter must be derived from at least one cereal plant. It may
however also comprise matter derived from one or more non-cereal plants.
The inclusion of non-above-ground parts of the plant is not particularly
desired within the scope of this process, but the presence of small
quantities of these non-above-ground plants does not invalidate the
application of this process.
Cereal plants which may be used in the application of this process may
include any cereal plant whose grain contains a sufficient quantity of
starch, preferably at least 20% by weight of starch in the whole plant.
They may in particular be corn, hard wheat, soft wheat, sorghum, oats, rye
and rice.
One of the advantages of the present process lies in the fact that it is
not necessary to perform a separation of the different parts of the plant,
for example the separation of the leaves and the stem, in order to apply
it. Thus, the step of cutting into fragments may be performed directly at
the time of harvest, in the field.
The invention may nevertheless be applied by using either the whole of the
above-ground parts of the plant which have previously been isolated, or a
major fraction of these isolated above-ground parts. A major fraction
should be understood as at least 80% by weight of the above-ground parts
of the plant. It may also be applied by using the above-ground parts of
plants belonging to different varieties or species.
By way of illustration, it is possible to use the process according to the
present invention by using, as above-ground parts, wheat straw and wheat
grain.
In addition, low quantities of additives may be added at any of the stages
of the process, if necessary.
The above-ground parts of the plant are advantageously cut into fragments
of average length between about 0.5 and 10 cm, and even more preferably
between 2 and 8 cm.
This cutting may be performed by any method known to a person skilled in
the art which leads to fragments of this size
According to a preferred embodiment of this invention, the fragments dried
in step b) to a residual humidity level of between about 7 and 13%.
This step is advantageously performed with a rotary dryer, for example a
temperature of 950.degree. C. for several minutes. However, it may also be
performed by any other drying process known to a skilled person.
Step b) of grinding or shearing is preferably performed until granules of
between about 0.5 and 1 mm in length are obtained. In the case of corn, a
fraction of the hard part of the cob, less than about 10% by weight of the
whole plant, may be discarded.
The size of the granules is measured by passing them through sieves with
decreasing diameter meshes. For example, granules having a size of between
about 0.5 and 1 mm pass through meshes of 1 mm in diameter but do not pass
through sieves with a diameter of 0.5 mm.
The size distribution of the granules obtained by this step is
advantageously the following:
between about 5 and 50% by weight of the dry matter of the granules having
a size of less than about 0.25 mm,
between about 5 and 40% by weight of the dry matter of the granules having
a size of between about 0.25 and 0.5 mm,
between about 15 and 60% by weight of the dry matter of the granules having
a size of between about 0.5 and 1 mm.
between about 1 and 10% by weight of the dry matter of the granules having
a size of between about 1 and 1.25 mm,
between about 0,5 and 7% by weight of the dry matter of the granules having
a size of between about 1.25 and 1.4,
between about 1 and 10% by weight of the dry matter of the granules having
a size of between about 1.4 and 1.7 mm,
between about 0,1 and 10% by weight of the dry matter of the granules
having a size of between about 1.7 and 2.36 mm, and
between about 0 and 10% by weight of the dry matter of the granules having
a size of greater than about 2.36 mm.
Step b) of grinding or shearing is preferably performed with a hammer mill
fitted with sieves of appropriate mesh sizes.
However, it may also be performed by any other device known to a skilled
person and giving equivalent results.
The granules produced in step b) of grinding or shearing may be immediately
formed, by any method known to a person skilled in the art using filling
of a mold and forming of the item under the effect of temperature and
pressure, in particular by molding in an injection press.
These granules may however, after grinding or shearing and adjustment of
the water content, be subjected to an extrusion step, so as to reduce the
volume/mass ratio of the granules.
This extrusion step is advantageously performed in a double-screw extruder,
whose screw profiles and temperature are selected by the skilled person as
a function of the granules to be treated, and the desired result. The
granules produced by this extrusion step may also be formed, as described
above, in an injection press.
The final products, and the intermediate products of the process, are also
objects of the present invention.
Thus, the present invention relates to plant matter granules with the
following size distribution, the percentages being expressed by weight
relative is to dry matter:
between about 5 and 50% of the granules having a size of less than about
0.25 mm,
between about 5 and 40% of the granules having a size of between about 0.25
and 0.5 mm,
between about 15 and 60% of the granules having a size of between about 0.5
and 1 mm.
between about 1 and 10% of the granules having a size of between about 1
and 1.25 mm,
between about 0.5 and 7% of the granules having a size of between about
1.25 and 1.4 mm,
between about 1 and 10% of the granules having a size of between about 1.4
and 1.7 mm,
between about 0.1 and 10% of the granules having a size of between about
1.7 and 2.36 mm, and
between about 0 and 10% of the granules having a size of greater than about
2.36 mm.
Such granules advantageously have percentages expressed by weight relative
to dry matter:
between about 20% and 60% of starch,
between about 3 and 20% of proteins,
between about 15 and 60% of cellulose, hemicellulose, and lignin,
between about 1 and 15% of lipids and,
between about 0.01 and 10% of sugars.
These granules, optionally having been subjected to an extrusion, have a
behavior comparable to that of a thermoplastic material, in other words
that under the effect of temperature, they can pass from a solid state to
a molten, pasty phase, and as a result can be injected into a mold and
then solidify on cooling. The melting of these granules may be achieved in
a plastification screw such as those used for synthetic plastics, such as
polyethylene, polypropylene and polystyrene.
The final products, in other words after forming, are thus composed of
granules bound together by melting of the meltable materials contained in
the above-ground parts of the plants. These materials have both
physicochemical and mechanical properties which distinguish them from
those already described in the state of the art.
In addition, these final products are biodegradable, ecocompatible and
recyclable by composting or by combustion.
A further object of the present invention is a material derived from plant
matter with a tensile strength, measured according to the international
standard ISO 527, of at least 10 N/mm.sup.2, and preferably at least 15
N/mm.sup.2, and a tension modulus of at least 1500 N/mm.sup.2.
Materials according to the present invention may have a bending strength,
measured as described in the standard NF EN 310, of at least 20 N/mm.sup.2
and preferably at least 25 N/mm.sup.2 and a bending modulus of at least
1500 N/mm.sup.2.
Such materials have the following composition, the percentages being
expressed in weight of dry matter,
between about 20% and 60% of starch,
between about 3 and 20% of proteins,
between about 15 and 60% of cellulose, hemicellulose, and lignin,
between about 1 and 15% of lipids and,
between about 0.01 and 10% of sugars.
They may be used for packaging, or for the manufacture of calibration
devices or for the manufacture of automobile interior fittings. They may
be in hollow, solid or profiled shapes. These materials are workable and
may be sawn, nailed, drilled and machined on a lathe. In addition, their
surface is smooth, not friable, and dust-free. These materials may be
glued and are compatible with surface treatments. They have in particular
a good compatibility with varnishes and paints.
The present invention is illustrated without in any way being limited by
the following examples.
BRIEF DESCRIPTION OF THE FIGURE
The FIGURE illustrates schematically the steps of the process which is the
object of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
EXAMPLE 1
Manufacture of Products According to the Invention from Corn, without
Extrusion.
Whole plants of corn of variety Cecilia were harvested in October, then
roughly cut up (from 1 to 5 cm). The composition of the plant matter thus
obtained was the following:
Hemi-
Cellulose cellulose Lignins Lipids Proteins Starch Sugars Ash
Humidity
17.2 18.6 1.4 2.7 6.5 36.1 5.9 2.6 10
(% by weight of dry matter)
The matter was dried in a rotary dryer (dehydrator: air temperature at
dryer inlet: 950.degree. C., residence time: 3 to 8 min.) to a residual
humidity of 7 to 13%. It was then ground in a hammer mill fitted with two
sieves of 4 and 6 mm diameter mesh.
The size distribution obtained was the following (4.3%>2.36 mm; 5.1%
between 2.36 and 1.7 mm; 4.3% between 1.7 and 1.4 mm; 3% between 1.4 and
1.25 mm; 5.5% between 1.25 and 1 mm; 31.9% between 1 and 0.5 mm; 22.2%
between 0.5 and 0.25 mm and 23.6% less than 0.25 mm).
The ground and dried matter was mixed with water in a planetary mixer so as
to obtain a homogenous mixture with an overall hydration level (Weight of
water/Total weight of wet matter) of 20%. The mixture thus obtained was
formed in an injection press (temperature of the injection chamber
150.degree. C., mold temperature 40.degree. C., limiting pressure 70 bars,
cycle length 35 s).
The formed object had:
a tensile strength characterized by an elasticity modulus of 2 365.+-.340
N/mm.sup.2 and a maximum breaking strength of 13 N/mm.sup.2, for a jaw
speed of 5 mm/min.,
and a bending strength characterized by an elasticity modulus of
2511.+-.230 N/mm.sup.2 and a breaking strength of 26.+-.3.6 N/mm.sup.2 for
a speed of 0.1 mm/s.
The tensile strength test was performed according to the international
standard ISO 527. The test pieces used were of type 1A and the jaw speed
was 5 mm/min. (tensile test ISO 527/1A/5).
The bending strength test was a three-point test as described in standard
NF EN 310. It was performed on rectangular test pieces of the following
dimensions: length 60 mm, width 10 mm, thickness 4 mm. The speed of the
cylindrical knife was 6 mm/min. The distance between the supports was 50
mm.
The identical tests were used in examples 2 to 4.
EXAMPLE 2
Manufacture of Products According to the Invention from Corn, with
Extrusion.
Example 1 was repeated up to the grinding step, then the matter was
extruded in a CLEXTRAL double-screw extruder, divided into seven zones.
The screw and temperature profiles were the following:
Zone Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Zone 7
Screw T2F C2F C2F Mal2 C2F C2F C2F CFC2 C2F
type
Screw 60 60 33 33 25 25 10 .times. 10 33 33 33 25
-25 25 33
pitch
Tempe- 14.degree. C. 14.degree. C. 15.degree. C. 17.degree. C.
15.degree. C. 29.degree. C. 24.degree. C.
rature
screw T2F: trapezoid groove transfer elements
screw C2F: U groove transfer elements
screw Mal2: mixed elements (bilobal)
screw CFC2: reverse thread.
The pitch corresponding to the screw is given in mm under each element. An
element measured 50 mm or 100 mm.
The water content of the matter was fixed at 20% by introduction of water
into zone 2 of the extruder. The flow rate of the dry matter was 27.9
kg/h, the screw speed was 210 r.p.m. The extrusion was performed without
head plate (no die), and the average residence time was 40 seconds.
The extrudate obtained had a residual humidity of 19%. It was formed in an
injection press (injection chamber temperature 150.degree. C., mold
temperature 40.degree. C., limiting injection pressure 40 bars, cycle
length 35 seconds).
The formed object had:
a tensile strength characterized by an elasticity modulus of 2780.+-.360
N/mm.sup.2 and a maximum breaking strength of 16.52.+-.2.7 N/mm.sup.2, for
a jaw speed of 5 mm/min.,
and a bending strength characterized by an elasticity modulus of
2830.+-.215 N/mm.sup.2 and a breaking strength of 35.2 N/mm.sup.2 for a
speed of 0.1 mm/s.
EXAMPLE 3
Manufacture of Products According to the Invention from Corn, with Grinding
in a Mill Fitted with a Sieve of 2 mm Diameter Mesh.
The raw material was whole corn plants of variety Cecilia (the harvest
conditions and composition are described in example 1).
The matter was dried in a rotary dryer (dehydrator: air temperature at
dryer inlet: 950.degree. C., residence time: 3 to 8 min.) to a residual
humidity of 7 to 13%. It was then ground in a hammer mill fitted with a
sieve of 2 mm diameter mesh.
The size distribution obtained was the following (0%>2.36 mm; 0.6% between
2.36 and 1.7 mm; 1.3% between 1.7 and 1.4 mm; 1.6% between 1.4 and 1.25
mm; 3.5% between 1.25 and 1 mm; 27.8% between 1 and 0.5 mm; 27.5% between
0.5 and 0.25 mm and 37.7% less than 0.25 mm).
The matter was extruded in a CLEXTRAL double-screw extruder. The screw and
temperature profiles were the following:
Zone Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Zone
7
Screw type T2F C2F C2F Mal2 C2F C2F C2F CFC2
C2F
Screw pitch 60 60 33 33 25 25 10 .times. 10 33 33 33 25
-25 25 33
Temperature 30.degree. C. 33.degree. C. 65.degree. C. 98.degree. C.
100.degree. C. 100.degree. C. 98.degree. C.
The water content of the matter was fixed at 25% by introduction of water
into zone 2 of the extruder. The flow rate of the dry matter was 28.3
kg/h, the screw speed was 210 r.p.m. The extrusion was performed without
head plate (no die), and the average residence time was 50 seconds.
The extrudate obtained had a residual humidity of 17.4%. It was formed in
an injection press (injection chamber temperature 135.degree. C., mold
temperature 40.degree. C., limiting injection pressure 150 bars, cycle
length 15 seconds).
The formed object had:
a tensile strength characterized by an elasticity modulus of 3152.+-.412
N/mm.sup.2 and a maximum breaking strength of 25.8.+-.3.2 N/mm.sup.2, for
a jaw speed of 5 mm/min.,
and a bending strength characterized by an elasticity modulus of
3428.+-.142 N/mm.sup.2 and a breaking strength of 43.4.+-.2.8 N/mm.sup.2
for a speed of 0.1 mm/s.
The water absorption after immersion of the object for one hour at ambient
temperature was 40%. The breaking time of the object subjected to static
tension (24 Newtons) under immersion was 5 hours.
EXAMPLE 4
Manufacture of Products According to the Invention from Wheat.
The raw material was whole wheat plants harvested and cut up so that the
straw had a particle size of less than 5 mm and that the grain was whole.
Its composition was the following:
Cellulose Hemicelluloses Lignins Lipids Proteins Starch Sugars Ash
Humidity
---38--- 1,4 7,2 46,8 0,1 2 91,3
(% by weight of dry matter).
The matter was extruded in a CLEXTRAL double-screw extruder. The screw and
temperature profiles were the following:
Zone Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Zone
7
Screw type T2F C2F C2F Mal2 C2F C2F C2F CFC2
C2F
Screw pitch 60 60 33 33 25 25 10 .times. 10 33 33 33 25
-25 25 33
Temperature 25.degree. C. 26.degree. C. 64.degree. C. 85.degree. C.
83.degree. C. 89.degree. C. 90.degree. C.
The water content of the matter was fixed at 25% by introduction of water
into zone 2 of the extruder. The flow rate of the dry matter was 40.5
kg/h, the screw speed was 210 r.p.m. The extrusion was performed without
head plate (no die).
The extrudate obtained had a residual humidity of 14.2%. It was formed in
an injection press (injection chamber temperature 127.degree. C., mold
temperature 30.degree. C., limiting injection pressure 150 bars, cycle
length 15 seconds).
The formed object had:
a tensile strength characterized by an elasticity modulus of 3411.+-.224
N/mm.sup.2 and a maximum breaking strength of 29.1.+-.1.6 N/mm.sup.2, for
a jaw speed of 5 mm/min.,
and a bending strength characterized by an elasticity modulus of
4027.+-.586 N/mm.sup.2 and a breaking strength of 60.1.+-.4.1 N/mm.sup.2
for a speed of 0.1 mm/s.
The water absorption after immersion of the object for one hour at ambient
temperature was 46%. The breaking time of the object subjected to static
tension (24 Newtons) under immersion was 9 hours.
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